Patients affected with a neurological disorder are prone to chronic pain or spasmodic muscle contractions. Such chronic pain and spasticity can worsen over time without treatment. Drugs or surgery can block undesirable neural activity; however, drugs have a slow time course and may have undesirable side effects and surgery is usually irreversible. An ideal block would be fast and reversible over extended periods.
Kilohertz high-frequency alternating current (KHFAC) provides a promising new technology that reversibly blocks action potentials while still preserving nerve viability. However, nerve block associated with KHFAC is associated with an onset response, during which the nerve fires rapidly for milliseconds to seconds. The onset response can cause brief, but intense, muscle contractions and pain. To improve the clinical utility of KHFAC, the onset response should be eliminated. Increasing neural temperature can induce block (e.g., due to altered ion channel kinetics) quickly and reversibly.